Glycol dehydrators

Here are two authoritative discussions " of troubleshooting in glycol dehydration plants. 

Here is another discussion of glycol plant troubleshooting from the article How to Improve Glycol Dehydration by Don Ballard. 

The most obvious indication of a glycol dehydration malfunction is a high water content or dew point of the outgoing sales gas stream. In most cases, this is caused by an inadequate glycol circulation rate or by an insufficient reconcentration of the glycol. These two factors can be caused by a variety of contributing problems listed below. 

In this example we selected a final outlet temperature of 100°F, This would be sufficiently low if the gas were only going to be compressed and dehydrated. For our case, we must also treat the gas for H2S and COt removal (Chapter 7). If we chose an amine unit, which we will in all likelihood, the heat of the reaction could heat the gas more than 10° to 20 T. making the next step, glycol dehydration, difficult (Chapter 8). In such a case, it may be better to cool the gas initially to a lower temperature so that it is still below 110°F at the glycol dehydrator. Often this is not possible, since cooling water is not available and ambient air conditions are in the 95°F to 1()0°F range. If this is so, it may be necessary to use an aerial cooler to cool the gas before treating, and another one to cool it before dehydration. 

At low vapor rates, valve trays will weep. Bubble cap trays cannot weep (unless they are damaged). For this reason, it is generally assumed that bubble cap trays have nearly an infinite turndown ratio. This is true in absorption processes (e.g., glycol dehydration), in which it is more important to contact the vapor with liquid than the liquid with vapor. However, this is not true of distillation processes (e.g., stabilization), in which it is more important to contact the liquid with the vapor. 

Most glycol dehydration processes are continuous. That is, gas and glycol flow continuously through a vessel (the contactor" or absorber ) where they come in contact and the glycol absorbs the water. The glycol flows from the contactor to a reboiler (sometimes called "reconcentrator or regenerator where the water is removed or stripped from the glycol and is then pumped back to the contactor to complete the cycle. 

The Canadian Standards Association Standard Z343 (CSA 1998) presents test methods for in-line and firebox flame arresters. In this standard in-line flame arresters are limited to only detonation types and firebox flame arresters are defined as flame arresters installed in an enclosnre, or system of enclosnres, where the mn-np distance is less than 1.5 meters and open to the atmosphere. Firebox flame arresters are commonly nsed on eqnip-ment designed to heat flnids in prodnction operations snch as indirect heaters, emnlsion treaters, and glycol dehydrators. The development history of this standard is presented in Section 2.3.2. 

In order to determine the optimum platform operating temperature it wos necessary to size the Glycol Dehydration System for the various platform operating temperotures considered. 

TABLE 2i GLYCOL DEHYDRATION STUDY SUMMARY OF RESULTS... 

Theoretical analysis and motion simulation work has resulted 1n a basic understanding of fluid motion Inside process equipment. In turn, the specific affects In two and three phase separators, treaters, glycol dehydrators and other process equipment has been analyzed. This research has lead to the establishment of process equipment sizing criteria for all types of vessel motion transmitted from the marine vessel, also the designs of baffling and other Internals to dampen and control the fluid motion have been established together with the optimization of equipment layout on marine vessels. 

Figure 20.8 shows a schematic flow diagram for a typical triethylene glycol dehydration system. The lean glycol is pumped to the top of an absorber column and flows downward in countercurrent contact with the water-wet gas entering the bottom of the... 

The dehydration unit at Acheson is described briefly by Lock (1997). At Acheson they dehydrate about 13 x 103 Sm3/d of acid gas (90% C02 and 10% H2S) in a glycol dehydration unit. This dehydration unit operates at about 1500 kPa. 

Removing excess water from the raw gas is often performed by a glycol absorption column. In some instances this facility is placed at the wellhead so that ice and hydrate formation in undersea pipelines is avoided. In a glycol dehydrator, the glycol absorbs the water which is then passed to a boiler which boils-off the water and returns cooled glycol (after heat exchange) to the absorber. There are several variants. ... 

The treated gas leaving the M D E A unit will require downstream dehydration since the pipeline gas specifications require a minimum water dew point. This is best achieved with a conventional TEG glycol dehydration unit, as the gas is very lean without condensable hydrocarbons. 

Ethylene glycol dehydration, 27 hydration, 5 Evaporation, 11,13 through stagnant gas, 629-632 EVF, 103... 

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